You can download free apps, but you may need to have a valid payment method on file, even if the app you want to download is free.
You can have a credit card / debit card on file and an Apple Account balance.
If you have set your Apple Account balance as your default payment method, your default payment method will be used first by Apple when you need to make a payment.
Free apps has also In-app pruchase.
See -> Buy additional app features with in-app purchases and subscriptions
Buy additional app features with in-app purchases and subscriptions
See also -> Apple Media Services Terms and Conditions
Legal - Apple Media Services - Apple
If you bought something then you have to pay, if you don't pay then you owe that amount to Apple until you pay.
Please check ⤵️
1.
If you see a message that says "Your account has been disabled in the App Store and iTunes", there is a problem with your payment method on your account, to resolve the problem you need help from Apple support, click -> contact Apple Support for help.
2.
If your Apple ID is locked or disabled -> If your Apple ID is locked or disabled - Apple Support (CA)
-> Get a verification code and sign in with two-factor authentication
Get a verification code and sign in with two-factor authentication - Apple Support
3.
See -> Add a payment method to your Apple ID
Add a payment method to your Apple ID – Apple Support (UK)
- If you want to change your card, you need to add first the new card, then remove the old card.
- or if you use your Apple Account balance, you need to set your Apple Account balance as your default payment.
See also -> Payment methods you can use with your Apple ID
Payment methods you can use with your Apple ID – Apple Support (UK)
fyi: Not all credit & debit cards seem to work with App Store / iTunes Store, try a different one, or preferably a credit card. If your card is not accepted as a paymenf method, you need to contact your bank.
If you have followed all the steps and instructions and if you still need help, get support from Apple directly -> Get Support or call Apple in your region see -> Contact Apple for support and service or check -> here for more support and assistance.